1. Technical Field
The present invention relates to a method of determining a threshold of detection for an edge of a printing medium, and to a printer operable to execute the same.
2. Related Art
There have been known ink jet printers operable to perform printing on a prescribed printing medium such as paper. As such printers, there has been known a printer which comprises: a printing head operable to eject ink toward the printing medium; a carriage on which the printing head is mounted; a platen facing the printing head; and an optical sensor for detecting an edge of the paper in the moving direction of the carriage. Such a printer is disclosed in Japanese Patent Publication No. 2004-351898A (JP-A-2004-351898). In this printer, an optical sensor is fixed to a carriage and detection of the edge of the printing medium is performed with the movement of the carriage. Also, in the printer, a protrusion (rib) for supporting a printing medium during the printing operation is formed on the platen.
In general, in order to detect the edge of the printing medium, a prescribed threshold is set with respect to a detection signal from an optical sensor. As a method of setting the threshold, there has been proposed a method of setting a threshold on the basis of an output signal of an optical sensor when the optical sensor senses a protrusion formed on a platen. Such a method is disclosed in Japanese Patent Publication No. 2003-260829A (JP-A-2003-260829).
However, JP-A-2003-260829 is silent about how to specifically process the output signal of the optical sensor in order to set the threshold.